My last post on determining occupancy for LEED projects did not discuss how to determine residential occupancy, an issue I've encountered recently.
Searching through the Credit Interpretation Rulings, I found a rather vague answer coughed up by the supreme court that is the CIR council (committee? emperor?) dated 2/14/2007:
Per the LEED NC v2.1 SSc4.2 ruling dated 12/9/2005, occupancy should be calculated using the number of bedrooms in the case of residential projects. Project teams should provide a narrative with calculations demonstrating how the total number of residential FTE occupants was calculated including indication of number of units, size of units (e.g. studio, one bedroom, two bedroom, etc.), and assumptions as to number of occupants per each size of unit.
So we base it on bedrooms... great! It would sure be nice to have actual guidance on how to transfer that into a hard number, but why make it that simple? Now we get into the sticky issue of what number to put to what bedroom count. Being lazy, I did not take the time to research average occupancy across the nation or anything like that. Instead I proposed the following:
Residential Occupancy Per Bedroom
- Studio/1 Bedroom - 1.5 occupants
- 2 Bedrooms - 2.5 occupants
- 3 Bedrooms - 3.5 occupants
- 4 Bedrooms - 4.5 occupants
Being the smart guy or gal that you are, you've probably picked up on "the formula". I think it's a safe bet to assume that a one bedroom could equally be expected to be occupied by 1 or 2 people, so I split the difference and assume 1.5. For additional bedrooms, it's likely to be occupied by either kids or roommates, but doubtful it will be occupied by additional couples.
I'd like to be clear that this assumption has not gone off for review yet, and I'm not going to spend a few hundred dollars to answer the question beforehand... I think this argument is reasonable, and expect it to be accepted, but don't want you to stake a large quantity of money on the fact that I'm right. If you have used different assumptions that worked or tried this one and failed, PLEASE be sure to comment on your experience below. Thanks!